Properly Matching a IDN URL

Question

I need help building a regular expression that can properly match an URL inside free text.

• scheme
  • One of the follow

Answer 1

John Gruber, of Daring Fireball fame, had a post recently that detailed his quest for a good URL-recognizing regex string. What he came up with was this:

\b(([\w-]+://?|www[.])[^\s()<>]+(?:\([\w\d]+\)|([^[:punct:]\s]|/)))

Which apparently does OK with Unicode-containing URLs, as well. You'd need to do the slight modification to it to get the rest of what you're looking for -- the scheme, username, password, etc. Alan Storm wrote a piece explaining Gruber's regex pattern, which I definitely needed (regex is so write-once-have-no-clue-how-to-read-ever-again!).